[glossary] Consolodate project codenames [zaqar]
[glossary] Consolodate project codenames [zaqar]

- Combine "Message service" entry with "zaqar" entry
  - Rename "Message service" to "Message service (zaqar)"
  - Link "zaqar" to "Message service (zaqar)"
  - Make sure description matches project.yaml

Implements: blueprint improve-glossary-usage
Change-Id: I815268a11f417813e70ff715515124cc5135457e

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals